-
1
Process Topping - Pulse bread, Parmesan, garlic and 2 Tbsp. butter in food processor until coarsely ground. Divide crumb mixture between 2 zip-lock freezer bags and freeze.
-
2
Cook pasta - Bring 4 quarts water to boil in large pot. Add 1 Tbsp. salt and macaroni and cook until barely softened, about 3 minutes. Drain pasta, then spread out on rimmed baking sheet and let cool.
-
3
Make Sauce - Heat remaining butter, flour, mustard, and cayenne in empty pot over medium-high heat, stirring constantly, until golden and fragrant, about 2 minutes. Slowly whisk in broth and cream and bring to boil. Reduce heat to medium and simmer until slightly thickened, about 15 minutes. Off heat, whisk in colby, cheddar, 1 tsp. salt and 1/2 tsp. pepper until smooth.
-
4
Freeze - Stir cooled pasta into sauce, breaking up any clumps, until well combined. Divide pasta mixture between two 8-in square microwaveable baking dishes. Cool to room temperature. Wrap dishes tightly with plastic, cover with foil, and freeze for up to 2 months.
-
5
Bake - Preheat oven to 375 degrees F. Remove foil from casserole and reserve. Microwave casserole until mixture is thawed and beginning to bubble around the edges; 7 to 12 minutes, stirring and replacing plastic halfway through cooking. Discard plastic and cover plan with reserved foil. Bake 20 minutes, then remove foil and sprinkle with 1 bag frozen bread crumbs. Continue to bake until crumbs are golden brown and crisp, about 20 minutes longer. Let cool 10 minutes.
